Process of dewaxing



March 15, 1938. L. D. JONES PROCESS OF DEWAXING 2 Sheets-Sheet i Filed Feb. 1. 1936 INVENTOR. LE0 DJoHEs BY W CL (MM/J1 ATTORNEY.

March 15,1938. D. JONES PROCESS OF DEWAXING Filed Feb. -1. 1936 2 Sheets-Sheet 2 INVENTOR. LEO DJoNEs 53y WW I W ATTORNEY.

Patented Mar.v '15, 1938 UNITED STTES PATENT OFFICE r aocnss i i r izwe A 7 Leo D. Jones, Philadelphia, Pa., assignor to The Sharples Specialty Company,

Philadelphia,

Pa., a corporation of Delaware Application February 1, 1936, Serial No. 61,845

7 @laims. (Cl. 233-'22) The present invention pertains to the continuous separation of materials of a viscous or semisolid nature from a liquid by means of centrifugal force. It is particularly concerned with the eflicient performance of a separating operation of this character in a case in which the viscous material is separated as the lighter efiluent from an inner radial zone of a, centrifugal rotor in which the liquid and lighter material are stratified by centrifugal subsidence.

' was conceived in connection with research on a stationary member which projects into the path of the wax and effects dislodgment of that wax by reason of the inertia of the wax itself. The member which effects such dislodgment may be a skimming nozzle of more or less conventional design, or it may be a dislodging knife or scraper adapted to cut into the wax layer for a. short distance and dislodge the wax layer so displaced from the centrifugal rotor. If a skimming nozzle is'used, the rotor axis may extend in any direction, but if a dislodging knife of non-tubular form is used, it is preferable that the rotor axis extend in a vertical plane and that the lower part of the rotor be circumferentially unobstructed at its center in order that the dislodged wax may fall out of the rotor by gravity.

Although an arrangement embodying a dislodging tool in the nature of a skimming nozzle or narrow knife might appear to be capable of removing efficiently any type of wax, difliculties are encountered in the practical application of the principle and it is to the solution of these difficulties that the present invention pertains.

In practical operation, many cases have been encountered in which an undesirably large proportion of oil is dislodged and discharged with the wax. Examination and analysis of the waxy material occupying the zone of the rotor of least radius from which this wax is dislodged indicate that this relatively high oil content is'. by no means characteristic of the material occupying this zone of the rotor and considerable dimculty has accordingly been-encountered in attempting to ascertain the reason for this high proportion of oil discharged with the wax in such instances.

After considerable study, the present applicant conceived the following theory as to the cause of the difliculty and it is upon this theory thatthe invention is based. When a heavy oil solutionalmost completely freed of wax and the material The invention lying within this heavy oil solution consists of wax particles occluding varying proportions of the oil solution. It is self-evident that the wax in the portion of the rotor close to its center will contain less oil solution than the wax further from thecenter of the rotor. While the innermost zone of the wax layer may therefore contain but a small proportion of oil, the wax zones extending between this innermost zone and the zone of the oil stratum contain progressively larger proportions of oil and are accordingly progressively softer in texture and more fluid by reason of the entrainment of such oil.

When we consider these facts as to consistency and fluidity of the material extending from an innermost radius of the wax zone to the substantially wax-free oil solution zone, the phenomenon of discharge of a waxy material containing an unexpectedly large ratio of oil can be readily understood. If we consider a case in which a dislodging tool of relatively narrow width is located in a. given plane and remains in that plane, we find it reasonable to suppose that the following type of separation occurs. When proximately its own width extending circumferlodged wax cake by flowing into the space previ-,

ously occupied thereby would flow into that space from all directions. In reality, however, we are concerned with a practical problem involving a more fluid mixture of. oil and wax in the zone lying radially without the dislodging tool than-in the portions of the rotor spaced longitudinally from the dislodging tool but in the zone of the radius thereof. There is thus a stronger tendency for the material lying outwardly of the tool to flow inwardly and replace the dislodged wax than for material occupying astratum of similar radius with theremoved wax, but longitudinally removed therefrom to flow into that space. As a consequence, the dislodged material is largely replaced by wax containing an undesirably large proportion of oil and it is this wax containing thehigh ratio of oil that isremoved in the subsequent operations.

The efiects discussed above are aggravated by reason of the fact that the waxy material occupying the innermost zone of material under treatment but substantially removed longitudinally from the zone occupied by the dislodging tool remains in the rotor an undesirably long time and has a still larger proportion of its oil solution removed incident to the prolonged centrifugal treatment caused by such retention. As progressively more oil is freed by centrifugal force from waxy material so located, that material becomes even stiffer than before, accentuating the chest of replacement of the dislodged wax strip by material lying radially without that strip instead of edecting the desired flow longitudinally of the rotor along the inner wax surface.

The present invention embodies method and apparatus for obviating the dimculties discussed above. It involves asan essential feature the mechanical dislodgment of wax along the entire inner surface of a mixture of this character in a centrifugal rotor. In the preferred embodiment of the invention a dlslodglng tool or tools are reciprocated longitudinally of the rotor with a sufiicient degree of frequency to avoid, to a large extent at least, the effects discussed above. By moving the dislodglng tool longitudinally in the rotor, it is possible continuously to remove war: of desirably low oil content. By moving the dislodging tool or tools in such a manner that they operate at frequent intervals upon material lying in substantially every part of the length of the rotor, a uniform removal of was: is attained without an undesirably high degree of discharge of oil therewith.

In the drawings accompanying this specification,

Figure l is a view partly in cross section and partly in side elevation illustratiru; one form of apparatus for use in the practice of the invention,

Figure 2 is a similar view illustrating an apparatus utilizing an alternative form of a dislodging tool,

Figure 3 is a detailed sectional view illustrating a modification of the embodiment of Figure I.

Figure 4 is a detailed plan view taken in the direction of the arrow 3-41 of Figure l, and

Figure 5 is a detailed plan view taken in the direction of the arrow d-Ei of Figure 2.

Referring to the drawings by reference characters. the numeral it indicates a centrifugal rotor adapted to receive through the feed conduit ii the material to be separated. This material is passed into the main body of the rotor through openings if. The rotor is preferably provided with a plurality of radially extending accelerator wings it and conically extending discs it. In the use of a centrifugal rotor of this character for the separation of wax from a heavier oil solution, the wax flows radially inwardly to the zone W of the rotor while the heavier oil solution passes radially outwardly to the 'zone 0 and is discharged through the outlets it. In the em bodiment of Figure l, a non-rotating dislodging tool, which may be, as illustrated, a skimming nozzle it, projects into the stratum of the rotating wax for continuously discharging it.

In the practice of the invention, special means are provided for reciprocating this dislodging tool longitudinally of the wax stratum within the rotor with sufficient frequency to avoid the objectionable phenomenon of the discharge of wax containing a substantially higher proportion of oil than the average oil content of the wax contained in the cylindrical zone having the general radius of the skimming nozzle. The reciprocatory movement of the skimming nozzle is preferably continued constantly during the separating operation and is also preferably of such an extent and velocity that the skimming name moves amines substantially the entire length of the wax zone within the rotor with substantial frequency. Special means are also provided for moving the skimming nozzle towardand away from theaxis of the rotor, thus changing the position ofv the inner surface of the wax stratum.

The means by which motion and adjustment of the nozzle are obtained are illustrated in Figure 1 and may comprise a shaft it which receives a reciprocating or rotary motion from any suitable source of power, (not shown), and which carries a crank arm it connected to a link it which is in turn connected to a lever 20 pivoted to a fixed support at 2i. The lever 2t is connected to a link it which is pivoted to a yoke 23 which is longitudinally fixed with respect to the skimming nomle it by means of a pair of confining sleeves 2d secured to the skimming nozzle. The skimming nozzle l 6 is, however, free to rotate within the yoke 23.

A shaft 2% is contained within a stationary housing Elli through which the skimming nozzzle it projects and this shaft carries a worm, (not shown), which meshes with a worm wheel 2i. The worm wheel El'l carries a key 28 which effects rotation of the skimming nozzle with the worm wheel by being received within a slot 29 in a sleeve'eid which surrounds the skimming nozzle and is secured thereto.

In the practice of the invention, the skimming nozzle is moved radially to the desired extent in to the wax stratum within the rotor by rotation of. a handle 33 secured to the shaft 25 and the skimming nozzle is reciprocated throughout substantially the entire length of the wax stratum of the rotor by the motion of the shaft ii and the parts connecting that shaft with the yoke 23. Wax removed from the rotor is discharged from the opposite end of the skimming nozzle at it. Oil is simultaneously discharged during the dis charge of the wax by passage through the outlets lt into the oil-receiving cover Ill.

The modification of Figure 2 is essentially similar to the invention illustrated in Figure 1, except that a dislodging knife 33 is substituted for the skimming nozzle it. This dislodging knife is preferably secured to a bar it which may be rotated to bring the knife into the path of the wax and reciprocated longitudinally of the wax stratum in the rotor by mechanisms similar to those illustrated in Figure 1 for efiecting rotating and reciprocating movements of the skimming nozzle in the invention of Figure 1. In the embodiment of Figure 2, wax dislodged by the knife dll'drops by gravity into a receptacle (it, while discharged oil is being continuously discharged into the oil cover 32. ,The modification of Figure 3 is essentially similar to 'the embodiment of Figure 1, except that in this modification, dislodging tools com prising a plurality of parallel skimming nozzles are employed, these dislodging tools 35 being secured to or integral with a central tube 36 which receives the wax efiluent therefrom. It will be self-evident that a plurality of dislodging knives of-the character illustrated in Figures 2 and 5 may be employed according to the same principle illustrated with respect to Figure 3 in the use of a plurality of skimming nozzles.

. Modifications of the particular design of appsratus illustrated will be obvious to those skilled in the art. I do not, therefore, wish to be limited in the interpretation of the scope of my invention except by the scope of the sub-joined claims,

Slit

prises broadly they practice of a process in which a dislodging tool is reciprocated longitudinally of the zone of the rotor occupied by a lighter and more viscous material stratifled' within the rotor by a process involving reciprocation of the dislodging tool or tools with suflicient frequency and to a suflicient extent to efiect discharge of such viscous material containing a proportion of the heavier efliuent not substantially greater than the proportion of such heavier efiluent occupying the general radial zone of the rotor of such dislodging tool. l

I claim:

l. The method of separating wax from an oil solution immiscible with said wax and having a higher specific gravity than said wax which comprises subjecting the suspension of the wax in the solution to a centrifugal ,stratifying operation to thereby eifect progressive separation of the wax from oil as it passes inwardly in the centrifugal rotor and removing from the rotor the wax subsided by said stratifying operation, said removal being accomplished by dislodging wax from the inner surface of the wax stratum under the influence of its own inertia, from relatively narrow axial zones of said rotor, the zone of performance of the dislodging operation being substantially constantly reciprocated longitudinally substantially through the axial limits of the wax stratum during the continued feed of oil solution to the rotor.

2. The method of separating wax from an-oil solution immiscible with said wax and having a higher specific gravity than said wax which comprises subjecting the suspension of the wax in the solution to a centrifugal stratifying operation to thereby effect progressive separation of the wax from oil as it passes inwardly in the centrifugal rotor and. removing from. the rotor the wax sublongitudinally substantially through the axiallimits of the wax stratum during'the continued sided by said stratifying operation, said removal. being accomplished by skimming wax in a confined stream from the inner surface of the wax stratum under the influence of its own inertia from relatively narrow axial zones of said rotor,

the zone of performance of the dislodging operation being substantially constantly reciprocated feed of oil solution to the rotor.

3. The method of separating wax from an oil solution immiscible with said waxand having a higher specific gravity than said wax which comprises subjecting the suspension of the wax in the solution to a centrifugal stratifying operation to thereby effect progressive separation of the wax from oil as it. passes inwardly in the centrifugal rotor and removing from the rotor the wax subsided by said stratifying operation, said removal being accomplished by dislodging wax from the inner surface of the wax stratum under the influence of its own inertia simultaneously from a plurality of relatively narrowaxial zones of said rotor, the zones of performance of the dislodging operation being substantially constantly reciprocated longitudinally substantially through the axial limits of the wax stratum during the continued feed of oil solution to the rotor.

4. The method of separating wax from an oil solution immiscible with said wax and having a higher specific gravity than said wax which comprises subjecting the suspension of the wax in the solution to a centrifugal stratifying operation to thereby effect progressive separation of the wax from oil as it passes inwardly in the centrifugal rotor and removing from the rotor the wax subsided by said stratifying operation, said removal being accomplished by dislodging wax from the inner surface of the wax stratum under the influence of its own inertia from relatively narrow zones of said rotor, the axial zone of performance of the dislodging operation being substantially constantly reciprocated longitudinally substantially through the axial limits of the wax stratum during the continued feed of oil solution to the rotor, said reciprocation occurring at a suficient rate to cause the discharge of a wax phase of substantially uniform oil content from the rotor.

5. The method of separating wax from an oil solution immiscible with said wax and having a higher specific gravity than said wax which comprises subjecting the suspension of the wax in the solution to a centrifugal stratifying operation I to thereby effect progressive separation of the wax from oil as it passes inwardly in the centrifugal rotor and removing from the rotor the wax subsided by said stratifying operation, said removal being accomplished by dislodging wax from the inner surface of the wax stratum under the influence of its own inertia simultaneously from a plurality of relatively narrow axial zones of said rotor, the zones of performance of the dislodging operation being substantially constantly reciprocated longitudinally substantially through the axial limits of the wax stratum during the continued feed of voil solution to the rotor, said reciprocation occurring at a sumcient rate to cause the discharge of a. wax phase of substantially-uniformoil content from the rotor.

6. The method of separating viscous or semisolid particles suspended in a liquid immiscible with said particles and having a higher specific gravity than said particles which comprises subjecting the suspension of the particles in the liquid to a centrifugal stratifying operation to thereby effect progressive separation of the particles from the liquid as they pass inwardly in the centrifugal rotor and removing from the rotor the particles subsided by said stratifying operation, said removal being accomplished by dislodging said particles from the inner surface of the stratum thereof under the influence of their own inertia, from relatively narrow axial zones of said rotor, the zone of performance of the dislodging operation being substantially constantly reciprocated longitudinally substantially through the axial limits of the stratum during the continued' feed of suspensionto the rotor.

..'7. The method of separating viscous or semi solid particles suspended in a liquid immiscible of the stratum thereof under the influence of their own inertia from relatively narrow axial .zones of said rotor, the zone of performance of the dislodging operation being substantially constantly reciprocated longitudinally substantially through the axial limits of the stratum during the continued feed of suspension to the rotor, said reciprocation occurring at a sufficient rate to cause I the discharge of a solid phase of substantially the rotor.

LEO D. JONES.

uniform liquid content from 

